1. Field of the Invention
This invention relates to a picture reproducing method and apparatus for reproducing a still picture recorded on a recording medium.
2. Description of related Art
In a conventional digital video tape recorder for digital recording/reproducing of video data, one frame of picture signals from an imager or other picture input signals is stored on a random access memory (RAM), in which the one-frame picture data are split into 8 by 8 pixel blocks and shuffled with a pre-set number of blocks as a unit. The resulting data is orthogonal-transformed, such as by discrete cosine transform (DCT), and quantized for compressing the one-frame video data. The compressed video data is framed and deshuffled, that is processed with an operation reversed from shuffling, on the RAM, for restoration to the original data array. An outer parity and an inner parity for error correction are then appended to the resulting data and encoded for recording. The encoded data is then recorded on a video tape.
In the playback system, the playback signals from the video tape are decoded, that is processed with an operation reversed from the encoding, to produce playback data, which is then error-corrected on the RAM using the outer parity and the inner parity, and shuffled. The resulting shuffled data is deframed and dequantized and the resulting dequantized data is inverse-orthogonal-transformed for expanding the one-frame playback data. The expanded one-frame playback data are deshuffled, that is processed with an operation reversed from the shuffling, and deblocked, for reproducing the video data having the original pixel array.
Meanwhile, the picture signals of the standard television system, such as the National Television System Committee (NTSC) system of the Phase Alternation by Line (PAL) system, are interlaced signals. Therefore, if, in the above-described conventional digital video tape recorder, the input picture signals are stored as still pictures in a RAM for shuffling or deshuffling, and the still pictures are directly recorded/reproduced as contiguous frame pictures, the picture portions having a significant amount of motion represent field period deflection on reproduction.
If one of the even-numbered frame and the odd-numbered frame making up an original one frame picture.times.2 is recorded as one frame for possibly evading the above-mentioned field period deflection, vertical resolution is deteriorated.
If the recording system has a dedicated still picture processor configured for storing one-frame video data in a RAM and the amount of motion within one frame is found so that a picture portion with a small amount of motion is directly outputted as a frame and the picture portion with a significant amount of motion is outputted as repetition of one of the fields, still pictures free of field period deflection can be recorded for reproducing still pictures of high definition by any reproducing device. However, since the dedicated still picture processor and a RAM for storing the video data for processing by this still picture processor need to be provided in the recording system, the circuit scale of the recording system is prohibitively increased.